Endocyclic Sulfur Research Articles

Die koordinationschemie CS-funktioneller verbindungen: VII. Elektrophiler und nukleophiler Angriff an Wolfram-CS 2-Komplexen

Five different tungsten CS 2 complexes of the type [W(CO) 3(diphosphine)(CS 2)] have been synthesized and their reactivity towards various electrophiles and nucleophiles has been studied. Methyl iodide alkylates the exocyclic sulfur atom, and thiiranes react by ring expansion to give 1,3-dithiolane-2-thione complexes. Coordinatively unsaturated metal fragments also add at the exocyclic sulfur to give CS 2-bridged binuclear compounds. Tributyl phosphine attacks either at carbon or at the endocyclic sulfur, depending on the nature of the diphosphine ligand, to give complexes of the betaine Bu 3P. CS 2 and thiocarbonyl compounds, respectively. Hydride reagents transfer H- to the carbon atom of the CS 2 complexes, but the alkylated CS 2 ligand is cleaved to give alkyl mercaptan and CS complex. Lithium alkyls give rise to thiophilic attack at the endocyclic sulfur, also to give alkyl mercaptan and CS complex.